Film capacitor and process for producing it

Abstract

At least a part of a protective layer (1, 4a, 4b, 5a, 5b, 6a, 6b,6c, 7, 8a, 8b) provided on the outer surface of a capacitance generating portion (2) of a film capacitor is constructed from a substantially non-oriented polyphenylenesulfide film (10). Since the non-oriented polyphenylenesulfide film (10) substantially does not accompany thermal shrinkage when it is heat stuck or soldered, and it absorbs the deformation due to the thermal shrinkage of other layers of the protective layer, the sticking stability and dimensional stability in the protective layer can be ensured. As a result, the thermal resistance of the protective layer and the thermal resistance of the capacitor can be improved as well as the simplification of sticking process or omission of an adhesive becomes possible. Moreover, this can serve to further miniaturization of capacitors.

We claim: 
     
       1. A film capacitor having a protective layer on at least a part of the outer surface of a capacitance generating portion constructed from the layers of a dielectric film and electrodes characterized in that at least a part of said protective layer is a substantially non-oriented film consisting of polyphenylenesulfide. 
     
     
       2. The film capacitor according to claim 1, wherein said polyphenylenesulfide film is thicker than said dielectric film. 
     
     
       3. The film capacitor according to claim or 2, wherein said protective layer comprises a plurality of layers, and at least a part of the plurality of layers are stuck to each other without using an adhesive. 
     
     
       4. The film capacitor according to any of claims 1 to 3, wherein said protective layer includes at least a layer of a biaxially oriented polyphenylenesulfide film, and a layer of a substantially non-oriented polyphenylenesulfide film is stacked on at least one surface of said layer of said biaxially oriented polyphenylenesulfide film. 
     
     
       5. The film capacitor according to any of claims 1 to 4, wherein at least the outermost layer of said protective layer is a biaxially oriented polyphenylenesulfide film. 
     
     
       6. The film capacitor according to any of claims 1 to 3, wherein said protective layer comprises a plurality of layers, and all of the plurality of layers are substantially non-oriented polyphenylenesulfide films. 
     
     
       7. The film capacitor according to any of claims 1 to 4, wherein the outermost layer of said protective layer is a substantially non-oriented polyphenylenesulfide film whose outer surface is thermally crosslinked. 
     
     
       8. The film capacitor according to any of claims 1 to 4, wherein the outermost layer of said protective layer is a biaxially oriented polyphenylenesulfide film whose outer surface is thermally crosslinked. 
     
     
       9. The film capacitor according to any of claims 1 to 8, wherein said film capacitor is a stacking type capacitor in which substantially planar layers of said dielectric film and said electrodes are stacked. 
     
     
       10. The film capacitor according to any of claims 1 to 8, wherein said film capacitor is a winding type capacitor in which said dielectric film and said electrodes are wound at a state that they are stacked. 
     
     
       11. A process for producing a film capacitor characterized in that a substantially amorphous and substantially non-oriented polyphenylenesulfide film having a relative crystallization index of not greater than 3.0 is stacked on at least a part of a capacitance generating portion constructed from the layers of a dielectric film and electrodes to make a stacked body, and said stacked body is heated at a temperature of not less than 100° C. and lower than the melting point of polyphenylenesulfide, and pressed in the thickness direction of said stacked body at a pressure of not less than 1 kg/cm 2 . 
     
     
       12. The process for producing a film capacitor according to claim 11, wherein said heated and pressed stacked body is further heat treated so that said substantially non-oriented polyphenylenesulfide film has a density of not less than 1,330 g/cm 3 . 
     
     
       13. A process for producing a film capacitor characterized in that a multi-layer film including at least one layer of a substantially amorphous and substantially non-oriented polyphenylenesulfide film having a relative crystallization index of not greater than 3.0 is made, said multi-layer film is heated at a temperature of not less than 100° C. and lower than the melting point of polyphenylenesulfide, and pressed in the thickness direction of said multi-layer film at a pressure of not less than 1 kg/cm 2 , and thereafter, said multi-layer film is stacked on at least a part of the outer surface of a capacitance generating portion constructed from the layers of a dielectric film and electrodes. 
     
     
       14. The process for producing a film capacitor according to claim 13, wherein said heated and pressed multi-layer film is further heat treated so that said substantially non-oriented polyphenylenesulfide film has a density of not less than 1,330 g/cm 3 .